The two are captured and sent to Stargate Command where they are interrogated. During a meeting it is learned that in the universe of the alternate SGC (there called SGA), ColonelJack O'Neill and Dr. Carter were married until O'Neill was killed defending the SGA. Also Teal'c is still an enemy of Earth as the First Prime of Apophis and has led the attack on the SGA, while Dr.Daniel Jackson never joined the SGA. The most shocking revelation is, however, that the Goa'uld have invaded Earth, conquered every major city and made slaves of the population.

Dr. Carter and Kawalsky are allowed to remain at the SGC. ColonelJack O'Neill visits Dr. Carter and she tells him about their marriage and how he died. She cries on his shoulder as he awkwardly comforts her. Later, Dr. Carter starts suffering from Entropic cascade failure—the result of two Carters in one universe—which she had predicted but had not expected to start so soon. If Dr. Carter and Kawalsky stay, she'll eventually die, but if they return to their reality the Goa'uld will kill them.

To prevent this a mission is planned in which O'Neill, the Dr. Carter and Kawalsky, Dr.Daniel Jackson, and Teal'c (in Jaffa armor) will go back to the alternate universe and contact the Asgard to free Earth. While the two Carters work on the Power booster device which will help them contact the Asgard, Kawalsky explains to Jackson how the Quantum Mirror works.

After the team goes through the mirror, they are able to capture the alternate Teal'c, who is then killed by the Teal'c of our reality. Teal'c then takes his place while the others activate the power generator and successfully dial the Stargate to get Dr. Carter to the Asgard homeworld. Apophis discovers Teal'c's betrayal and the team is captured. Apophis questions them and has the alternate Major GeneralGeorge S. Hammond killed. Even after they then inform him of the alternate reality they come from, he threatens to kill Jackson. Before he is able to do so the Asgard arrive, forcing most of the Jaffa to flee and resurrecting Hammond. The mission completed, the non-alternate team returns home, but not before O'Neill and the alternate Carter share a kiss.

Interviewer: Stargate... what do you know about the Stargate?Alternate Carter: What do I know!? Everything!! We've been through this!!Interviewer: Well, let's go through it again.Alternate Carter: For cryin' out loud...

Jackson: Well, this can't be the Dr. Carter I met in the alternate reality, she's... dead.O'Neill: All right, uh... just to clarify, this Carter is from an alternate alternate reality?Jackson: Apparently.O'Neill: Anybody else have a problem with that?Teal'c: Which reality is actually real?O'Neill: Thank you, Teal'c.

O'Neill: So it's possible there's an alternate version of myself out there that actually understands what the hell you're talkin' about?

O'Neill: Alright, uh, just to clarify, this Carter is from an *alternate* alternate reality?

O'Neill: For all we know you could be her evil twin. But then we'd be dealing with clichés, and you know how I feel about those. No, actually, you know how I feel about those.

Alternate Carter: (annoyed) You think your being in the Air Force could have made that big a difference?Carter: No. I just said it made a contribution.Alternate Carter: (more annoyed) And therefore I didn't?O'Neill: Ladies...Sams...We're all in this reality together.

Carter: If the Asgard could design this to give the gate extra juice, then they're just the little green men we're looking for.O'Neill: They're grey, actually. Roswell grey to be exact.

(Jack walks in on Teal'c and Teal'c's dead alternate reality counterpart, whom Teal'c has just shot.)O'Neill: The idea was to zat him.Teal'c: As I said, O'Neill, ours is the only reality of consequence.

The alternate Dr.Samantha Carter experiences what comes to be called "temporal entropic cascade failure" as a result of there being two Carters in the same reality. However, in the Season 9 episode "Ripple Effect", there are at least 18 different SG-1 teams in the same reality, and none of them are effected by temporal entropic cascade failure. In that episode, Dr. Bill Lee theorised that this was due to the proximity of all the realities to each other.

Most likely because they came through the black hole instead of the Quantum Mirror.

While Dr.Daniel Jackson is searching through the alternate realities in the Quantum mirror, one of the realities he comes across is a beach with a moon and a gas giant planet visible in the sky. This is the beach on Nem's planet Oannes from the season 1 episode, "Fire and Water."

MajorSamantha Carter claims that "...In order to dial the Asgard homeworld they had to provide us with a generator that transferred power to the Gate's capacitors." Actually, ColonelJack O'Neill built the device using the knowledge of the Ancients. (SG1: "The Fifth Race") However, it is possible that the device O'Neill built only worked once, and had to be replaced. Alternatively, the Asgard could have upgraded the device's design, and given them a better one.

This is unlikely due to the fact it was depleted when they started on it.

The Asgard homeworld address shown being dialed is different from the one used in "The Fifth Race". (it would appear these are the same symbols just orientated differently)

When Dr.Daniel Jackson and Teal'c go through the Quantum Mirror back to their reality. They would have appeared on opposite sides but they appeared as if it was a mirror image. Teal'c touched the mirror with his right hand and Daniel touched it with his left. Though on the other side Daniel is touching it with his right hand and Teal'c was touching it with his left hand. They needed to have switched sides as they would have came through in the same position but this did not happen.

When the team travels to the alternate reality, both the corridor in front of the storage room and to the side are damaged and weren't before. Its acted like it all happened due to Kawalsky's grenade but while the side hallway definitely should've been damaged by it, the area in front of the storeroom was too far away from the explosion.

When the Jaffa are fleeing through the Stargate, the last one has the tip of his staff weapon sheared off by the closing gate. At the time there were no SGC personnel in the control room to turn off the gate (they were all in the gate room) and the gate wasn't near its automatic cut-off limit so it shouldn't have closed until the object was completely through. It's possible that the Asgard (who have been shown to have superior control of gates) turned the gate off remotely.